A bug has been discovered in the iOS app that prevents syncing in extreme quality, and that resets the setting repeatedly. There will be a fix included in the next update of the app.
please hurry... this bug has been driving me crazy!
How is this still a problem?!
I'm having exactly the same problem and I really need it fixed soon. And yes I 've got the latest version of spotify, I deleted and redownloaded to make sure.